Chemical method of etherifying dextran



Patented June 11,

METHOD OF ETHERIFYING l DEXTRAN Grant 1.. Stahly" and Warner w. canson, Columbus, Ohio, assignors to Commonwealth Engineering Corporation, Wilmington, DeL, a

corporation of Delaware NojDrawing. Original application July 29, 1937,

Serial No. 156,426. Divided and this applica tion February 4, 1938, Serial No. 188,723-

7 Claims. (01.260-209) This invention relates to the production of polysaccharide materials by the action of various micro-organisms on suitable culture media, and to processes for converting these polysaccharides into their ether, mixed ether, ester, mixed ester or mixed ether-ester derivatives.

It is the object of thisinventionto produce polysaccharide materials by the action of various micro-organisms on suitable culture media and 10 in particularto producedextran; and to there:

after subject the polysaccharide materials such i as dextran to a process of etherification or esterification either while the materials are in the, culture media or after separation therefrom, so.

as .to produce the new products otresinouscharacter such as the benzyl ether. of dextran, the,

butyletherof dextrametc. 1

Thepclysaccharides are produced by inoculating media containing sucrose, nitrogenous compounds and various saltswithbac-teria of those that produce the polysaccharides known as dextrans. lThe twotypes of polysaccharides are. distinguished irom one anotherby the fact that en hydrolysis with acids or, enzymes, the dextransyield only dextrose. while the \levans yield only,levul0se. As speciflc examples, Bacillus:

mesentericus B. subtilis, B. megatherium; Pseudomohas prum', Ps. prunicolo ,orPs. phaseolz" may be employed for the productionof the levan type of polysaccharide, while Leuconostoc mesene terozdes or L. demtranicum may be used for the production of the dextran type. d The culture media employed must contain some sucrose; ,this can beyeither refined or crude sucrose, molasses or any} similar SUCI'OSGCQHFM taming material i y beadded in th mm of commercial peptone, beef extract or other nitrogen containing materialQ 1 If inolasses is used as the sucrosesource, nitrogenous compounds in sufficient quantity are present init so "that. none need be added. r Salts such as di 5 potassium phosphate and sodium chloride are also added! As a specific example, a typicalmedium may contain: sucrose, 5+l0%1peptone, 0.1%,

trality. 1 I

The production of the'polysaccharide is favored] by keeping the reaction of the media slightly alkaline throughout the period of rennentano I This may be accomplishedj by the" periodic addijtion ofallrali to the fermenting media or by using an excess of calcium carbonate in the media.

After inoculation the cultures are incubated at the temperature most favorable to the growth of the micro-organism being used. For one of the 5 preferred forms, Leuconostoc mesenteroides, this temperature is around 25 degrees C. The progress of the fermentation may be followed by periodically removing samples of the fermenting culture media and precipitating theflpolysaccharide 10 contained in them by the. addition of three to five times their volume of alcohol. The precipitated polysaccharide may then be weighed. When a maximum of polysaccharide has been formed the culture media are ready, for the 15 etherification or esterification. processes. The

. length of time necessary for the maximumof polysaccharide to be formed will vary with the organism employed, the temperature of incubation, the concentration of sucrose and other 20 known genusand species. These bacteria may be placed in one of ttwogroupings, those that q produce polysaccharides known as levans, or

. der,reduced pressure at a temperature of40 to 50 degrees C, to approximately one-fourth its originalvolume. The solution is then poured, with .30 stirring, intofthree to 'fivetimes itsvolume of alcohol orjacetone. The polysaccharide may be precipitated, directly from the fermented culture media by the addition of alcohol or acetone,

but it is then necessary to use a considerably 85 larger amount of the precipitating agent.

For thepreparation of the ether and esterderivatives of these polysaccharides it is not necessary that they first be isolated from the culture media in whichthey were formed. Instead the 40 neoessaryy ffiagents maybe added directly to the fermented, media, and after completion of the reaction, the. ether, ester, or mixed ether-ester derivatives can be recovered from the mixture, either by a simplemechanical process in case the product is water insoluble, ,or by the use or speciflcprecipitating agen dipotassium phosphate 0.2 and sodium chloride 3 0.1%, .TheIpHoi the mediumpreferablyis ladso justed to slightly on the alkaline slde oi, neu-J If, however, ,theupolysaccharide is not removed from theculture solution before esterificationor etherificatiom. the product obtained is a mixture of compounds. It will contain, besides; the ethers and/or esters oi the polysaccharide, the corre-.

H spending derivatives of any excess sucrose or metabolic "products. remaining in, the ifermented cultureflmedia. In some cases, this may be de- 56 sirable since a blending of these various derivatives yields a product with a range of solubilities. However, in cases in which a product with the specific properties of the polysaccharide derivative alone are desired, it is necgssaryeither to separate the dextrans or levans from the culturemedia before chemical treatment, or else to remove the undesirable by-products, from the mixture obtained by the direct treatment of the fermented media, by the use of specific solvents.

Whether the fermented media are treated directly, or the polysaccharides first isolated by If the fermented culture medium itself is used,

" the amount of water present should be so regulated by concentration or dilution to again yield approximately a 10 per cent solution of the alkali. After addition of the reagents the mixture is heated for a predetermined time, usually i-to 6 hours, at a temperature anywhere from 80 to 130 degrees C. This temperature depends on the derivative being prepared.

In general, the higher the temperature and the longer the period of heating the greater will be the number of hydroxyl groups in the polysaccharide which will be substituted by the organic radical of the halide compound used. The temperature and time of heating employed is consequently governed by the type of product desired. The organic halide used may be any member of the aliphatic series such as methyl chloride, ethyl chloride, propyl or isopropyl tions and the particular halide employed. As an chloride, butyl chloride or any of its isomers,

etc.,'or any one of 'the araliphatic series such as benzyl chloride.

The aliphatic derivatives are water soluble,

at least as high as the butyl derivative. The benzyl ethers are generally water insoluble. Re-

, gardl'ess of .the type of organic halide used, in-

creasing the proportion of halide to polysac charide, running the reaction at a higher temperature and for a longer period of time will generally result in a decreased water solubility for the products obtained.

It is to be understood that the organic halide used may be either the chloride, bromide or iodide derivative- For purposes of economy, the chlorides are generally employed. 1

At the conclusionof the reaction period excess halide is recovered by any suitable process such as steam distillation. The product isisolated by mechanical means if it is waterinsoluble or by precipitation ifit is water soluble.

' The process may be varied by the simultaneous introduction of two ormore organic halide com-'- pounds into the reaction mixture, in which .case the product will be a mixed ether; or a particular ether derivative may be prepared and the product from the reaction then treated with a different organic halide to yield a mixed ether derivative. Again, an ether derivative may be prepared and then further treated with organic acid chlorides, acid anhydrides'and the like for the'preparation of mixed ether-ester derivatives. Such variations in treatment are. of course, almost without number.

example, the benzyl ether of dextran is a water insoluble material which resists the action of the common organic solvents, while the butyl ether of dextran is water soluble. a

The following are examples of specific practices of our method for the production of new prod- It will be understood we do not desire to be confined to the detailed proportions, temperatures and pressures, although we are reciting hereinafter those that We have found to be the preferred temperatures and other conditions.

It will be further understood that it is comprehended within this process the production of a large number of allied materials.

It will be further understood that we are illustrating the process and the materials that can be produced by typical materials within which we comprehend other similar new materials.

Exsmma I Benzyl ether derivatives This process may be carried out directly on the fermented culture media containing the polysaccharide, such as dextran, although the same process can be employed with the extracted dextran after it has been removed from the culture media. This statement applies to the other examples hereinafter recited.

To a portion of the fermented culture medium in which the polysaccharide has been produced and in which there is approximately 30 gm. of the polysaccharide, is added 90 gm. of benzyl chloride and 40 gm. of sodium hydroxide. The resulting mixture is heated for approximately five hours. If the temperature is held at 80 to 85 degrees C., the crude'product is light orange in color and soft and rubbery inconsistency. When benzylation process, the solubilities in various solvents of the resulting products are varied.

These products are substantially insoluble in water. l

Exmna 11 W ether derivatives To a portion of the fermented culture medium containing 30 gm. of dextran, we add 120 gm. of

butyl chloride and 40 gm. of sodium'hydroxide' The mixture is .heated at 100 degrees C. for four hours. The derivative is an amorphous 1 mass that is water soluble.

Exsurm: III M ized benzyl ether-butyl ether derivatives To. a water solution of the butyl ether derivative is added benzyl chloride and sodium hydroxide in the proportion of 30 gin. of the butyl ether; 90 gm. of benzyl chloride and 40 gm. of sodium hydroxide. 'I'he'mixture is heated at to 70 degrees 'C. for a period of five hours. After removal of excess benzyl chloride and benzyl'alcohol by steam distillation, the: resulting product is isolated asa'rather iii-m and'leathery amor- EXAMPLE IV Beta-hydromy ethyl ether derivatives changed to a light brown. Since the beta-hydroxy ethyl ether derivative is water soluble it was isolated by precipitation with acetone. The product was an amorphous, hygroscopic mass.

EXAMPLE V Mixed beta-hydroxy ethyl ether-benzyl ether derivatives To a water solution of the beta-hydroxy ethyl ether derivative was added benzyl chloride and sodium hydroxide in the proportion 30 gm. of the ether, 90 gm. of ,benzyl chloride and 40 gm. of alkali. The mixture was heated at to degrees C. for five hours. After removal of excess benzyl chloride and benzyl alcohol by steam distillation, the resulting product appeared as a golden-brown, rather moist and stringy amorphous mass.

The p oducts recited herein are claimed in our co-pending application Ser. No. 156,427, filed July 29, 1937.

It will be understood that we desire to comprehend within this invention such modifications as come within the scope of our claims and our invention.

It will be understood that the temperatures and times are relative and may be varied within reasonable limits to secure the objectives desired.

This application is a division of our application Serial No. 156,426, filed July 29, 1937.

Having thus fully described our invention, what we claim as new and desire to secure by Letters Patent is:

1. In a process of making benzyl ethers oi! dextran, dissolving the dextran in a water solution of suflicient sodium hydroxide to keep the solution alkaline throughout the period of the reaction, adding benzyl chloride in the proportion of slightly more than one mol of the chloride for each hydroxyl group in the carbohydrate, and heating the mixture to form the benzyl ethers of dextran.

2. In a process of producing ethers of dextran, the step of forming an alkaline solution of dextran in water with sodium hydroxide to keep the solution alkaline throughout the reaction period, and the step of etherification with benzyl chloride.

3. In a method of producing ethers of dextran, the steps of (a) forming a water solution of dextran; (b) adding benzyl chloride and sodium hydroxide; and (c) heating the mixture for a sufficient period to react the dextran and benzyl chloride in an alkaline conditionto produce benzyl ether of dextran.

tion, benzylating the solution, and heating the mixture to form an ether of dextran.

5. In a process of making ethers of dextran, dissolving the dextran in an alkaline water solution and maintaining the alkaline character of the solution throughout the period of the reaction, benzylating the solution and heating the mixture to form an ether of dextran, and purifying the product by distilling off the excess benzylation reactants.

6. In a method of producing benzyl ether of dextran, reacting approximately 30 gm. of dextranin water with approximately gm. of benzyl chloride and approximately 40 gm. of sodium hydroxide at temperatures ranging from 80 to degrees C. for a period of from 4 to 6 hours.

7. In a process of making ethers of dextran, dissolving the dextran in an alkaline solution and maintaining the alkaline character of the solution throughout the period of the reaction, subjecting the solution to an aralkyl etheriiying agent, and heating the mixture to form an ether of dextran.

GRANT L. STAHLY. WARNER W. CARI-SON. 

